Lifting-jack.



CHARLES F. SCHEBENZEL. 0F SAN FRANCISCO, CALIFORNIA.

LIFTING-JACK.

Specification of Letters Patent.

Patented Apr. 2d, 1917.

Application led July 24, 1916. Serial No.` 110,819.

To all whom z't may concern."

Be itl known that I. CHARLES F. SCHEREN- zEL. a subject of the Emperor of Austria. residing at San Francisco. in the county of San Francisco and State of California .have invented certain new and useful Improvements in Lifting-Jacks. of'which the following is a specification.

This invention relates to that class of lifting jacks which are actuated through the agency of compressed air.

The objectof my invention is to produce an inexpensively and compactly constructed jack which will be rapid and powerful in operation and which is provided with automatically acting devices for regulating the action of the power lnedium at predeterminedelevations of the jacks vlifting-bar.

T he. means whereby these ends are accomplished is described in the following Vspecification and illustrated in the V4accompanying drawing which shows in transveise vertical section an embodiment of the invention.

The reference numeral 1 denotes the frame or standard of the jack which is bored t-o provide a. cylindrical chamber 2 or cylinder." as it will be hereinafter designated.

Mounted for reciprocatory movements in said cylinder is a piston 3 carrying packing l. Rigidly secured to said piston is a lift--v ing-bar 5 provided with ratchet teeth 6 for engagement by a pawl T whichis pivotally mounted on a pin 8 which is supported in lugs` such as 11. provided on the standard.

9 is a relief valve which is vieldingly held against its seat, as shown. to normally close a duct leading from the external atmosphere, and a. passage 11 which connects wit-h the bottom of the cylinder 2. Said passage has a branch connection 12 with a detachable flexible tube 13 extending from an air pump or compressed air reservoir.

A spring-closing check valve 1l is provided for the passage 1:2 and is displaced from its se'at- 141 by the tube coupling 15 when the latter is screwed into the socket therefor in the standard. A spring-pressed detent 16 is provided to engage in a selected one of thenotches 1T or 1S of the pawl to releasably hold the same in position to engage the bar-teeth 6. or otherwise.

Adjacentto the upper and lower ends of the lifting bar 5 are provided protuberances 19 and 191 extending outside of the lplane of the intermediate ratchet teeth 6 lfor the purposevof inuencing-the pawl at g 1 or near the ends of the bar's travel to eifect the reversal of the bar. vThat is to say, when tlns bar approaches the end of an upward stroke. the protuberance 191 encouru' ters the pawl to swerve the same out of engagement with the ratchet teeth, and cause the arm 20 of the pawl to. be swung below the position in which it. is indicated by broken lines 201 in the view. to engage and push down the Avalve stem 91 t0 Open the. valve '9.

ll'hen this occurs. the air under pressure escapes from the cylinder and` allows the piston 3 and the lifting-bar to descenduntil the protuberance 19 swerves the pawl into engageable position with respect to the ratchet teeth. and withdraws the pawl from the stem 91 when tlie spring 10 asserts itself to close the valve 9.

If air under sufficient pressure is admitted through the t-ube 13. the lifting-bar will again be caused to ascend. and so on. The pawl thus serves to influence the valve for the escape, of compressed air to the atmosphere. and also serves to support the lifting arm at. various elevations should the air supply be interrupted as. for example. when a load is to be sustained for a considerable time.

Besides being controlled automatically to ele'ct the reversal of travel of the liftingbar atthe terminations of its strokes. the bar may be lowered before reachingits highest elevation by the operator presslng the arm Q0 downwardly to open valve 9.

The invention is of simple construction. convenient to handle. and may be operated in an inaccessible place by regulating the supply of compressed Aair either atthe source of supply. or by means of a valve provided for the tube 13 at a distance from where the jack is to be employed.

For automobile work. it is peculiarly advantageous by reason of itssmall size. which enables it. to be carried in the machine and by reason of compressed air being usually available.

1. In a lifting-jack, the combination wit-h a standard having a cylindrical bore, a piston therefor. anda lifting-bar oper able with said piston. of means t-o' supply air under preure into said bore below the lifting-bar, a relief valve, and means e11- compressed air and a' standard, a lifting-bar elevations, a relief valve for regulating the cape of said power pressure of the power medium, and means provided on said bar and engageable with the pawl when the bar approaches the upper end of its stroke whereby the pawl is caused to effect the relief valve for the esmedium and enable the bar to descend.

3. ln a lifting-jack of the class described, a standard, a-lifting-bar having a series of teeth, a pawl provided on said standard and adaptedto engage the teethof said bar for releasably supporting the same at various elevations, a spring-closing relief valve for regulating the pressure of the power lnedium, means provided on said bar and engageable with the pawl when the bar, approaches the' upper end of its stroke whereby the pawl is caused to elect the relief valve for the escape of said power medium and enable the bar to descend, and a second means provided 0n said bar and operable when the latter reaches the lower end of its stroke to render said relief, valve closed and thereby enable the power medium capable of elevating the lifting-bar.

el. In a lifting-jack o the class described, a. standard having a cylindrical bore, a piston operable within said bore, a lifting-bar secured to said piston and provided with a series of teeth, a pawl supported on said standard and engageable with the successive teeth as the lifting rod is elevated, means for eli'ecting said pawl to engage the same with the teeth at the termination of a downward stroke of the bar and means to disengage the pawl from the teeth at the termination of an upward stroke of the bar.

5. In a lifting jack of the class described, a standard having a cylindrical bore, a piston therefor, a lifting-bar operable with' said piston, of means to supply fluid under pressure into said bore below the piston to effect the elevation of the lifting-bar, a relief valve for the escape of compressed Huid from said bore, and means influencing said valve and actuated by the alternate strokes of the lifting-bar whereby reciprocatory motion is afforded to the latterthrough the dii'erenoes in Huid pressures obtaining under said piston.

Signed at. San Francisco, Calif., this 13th day of July, 1916.

CHARLES F. SCHERENZEL.

Witnesses i MrRoN WOLF, O. M. HART. 

